Apparatus and method for issuing and authenticating securities, etc. using digital watermarking

ABSTRACT

Simultaneously with a robust watermark and fragile watermark or semi-watermark is embedded into conventional securities, etc., such as gift coupon, various kinds of ticket, coupon, electronic stamp, bond &amp; debenture, note, stock certificate, lottery, paper money, check, etc. and various kinds of public documents including certificates, etc. requiring confirmation and authentication (hereinafter, referred to as “securities, etc.”) in the form of digital file. Such watermark-embedded securities, etc. are conveniently issued on-line and are printed out in the form of paper through a printer. The printed securities, etc. are used off-line and are authenticated by determining the forgery or alternation by means of photocopy, etc. through the detection of the embedded watermark,

TECHNICAL FIELDS

[0001] The present invention relates to apparatus and method for issuingand authenticating securities, etc. using digital watermarking.

[0002] More particularly, the present invention relates to apparatus andmethod for embedding watermark into the conventional securities such asgift coupon, various kinds of tickets, coupon, electronic stamp, bond &debenture, note, stock certificate, lottery, paper money, check, etc.which are in a digitalized file form, and various public documents beingissued requiring confirmation and authentication (hereinafter, refer toas “securities, etc.”), and for issuing such watermark-embeddedsecurities, etc. on-line in a simple and safe manner. Moreover, indetermining whether the above securities, etc. which have been printedout from the printer, etc. then issued are forged and altered throughphotocopying, etc., the present invention relates to apparatus andmethod for accurately and easily determining the authenticity of thesecurities, etc. through the detection of the embedded watermark.

[0003] The “securities, etc.” used in the present invention is a terminclusive of all papers (tickets, gift certificate, electronic money,etc.) having commercial value or paper money value, i.e. having a legalright as well as certificate requiring authentication or certificatehaving various kinds of primary information.

BACKGROUND ART

[0004] Together with the recent rapid growth of computer science,various contents are digitalized according to the improvement on theefficiency of the high-technology apparatus including A/D or D/Aconversion device such as printer, scanner, digital camera, etc. Also,as the process of generating securities, etc. is digitalized, thetechnique forging or altering such is being developed day by day.

[0005] In this regard, the forged securities, etc. refer to securities,etc. that are newly made one similarly or identically with self-genuinecopy (original copy) by a person who has no right to issue. Such forgedsecurities, etc. are directly printed by using scanner or printer, orphotocopied by using a color photocopier.

[0006] Further, the altered securities, etc. mean securities, etc. withtheir appearance changed wherein the change is made to the contents ofthe genuine copy of the securities, etc. For example, such alterationincludes changing the face value amount from the low amount to a higheramount, or increasing the value of security by changing the issue dateor interest payment date or changing specific particulars such as thename of the certificate, etc.

[0007] In accordance with the growth of forgery or alteration technique,the forged/altered securities, etc. have become very precise renderingthe determination by naked eye to be ever more difficult. Specially,when the forged/altered security is circulated, the entire financemarket including the security market will become chaotic, andfurthermore, a national economic dislocation may arise. In order toprevent such chaos, various preventive measures such as below areestablished and managed.

[0008] 1. Method Using Special Paper

[0009] A method using special paper includes use of watermark paper,pre-printed pattern, OMR sheet or chemical watermark, etc.

[0010] Watermark paper is manufactured by gluing two sheets of paperinto one. When processing pulp to make paper, a method for revealing anappearance of pattern at light exposure by inserting pattern of adesirable shape using wire into the laminated paper (paper made bygluing two sheets of paper) is used widely for a primitive prevention offorgery.

[0011] There is also a method using security thread invisible except forwire or visible hidden line. The security thread includes several typessuch as insertion of consecutive characters, luminescence at theexposure of ultraviolet light, and appearance of particular figure orcharacters at the rise of temperature when rubbed by hands, etc.

[0012] The pre-printed pattern is technically difficult and rare, whichleaves very little room for time or space for its use. Thus, when makingsecurities usually small in numbers such as gift certificate, OMR paperis widely used which has better strength than other paper and triggersrejection reaction against the color photocopier.

[0013] The chemical watermark employs chemicals which actually havesimilar features as the watermark paper. The chemical watermark treatedwith chemicals is far more cheap and convenient to use than thewatermark paper, and an effect similar to watermark paper can beobtained in its functional aspect. Thus, the chemical watermark isvaluably used.

[0014] 2. Design Method

[0015] The design method includes a hologram application method, amethod using special pattern such as duplication prevention figure orconcentric fine line, a method using micro-printing and a method ofmatching front/back copy, etc.

[0016] The hologram application method is a method designing andtranscribing a desirable shape into the film, and heating thetranscribed film for stamping on the paper. It is possible to stamp anydesirable figure in the films such as various color of gold film, silverfilm, blue film, green film, black film, rainbow-color film and hologramfilm, etc. in similar cases. During the photocopying process, the lightcannot penetrate the film, so the stamped portion is photocopied inblack. Thus, a form different from the original is obtained so thatforgery including duplication is prevented.

[0017] A method using special pattern such as duplication preventionfigure or concentric fine line is very useful in preventing a forgerycase which uses scanner or photocopy machine. When scanning orphotocopying, the light is flashed uniformly from one end to the otherend and the dark portion of the refractive wavelength wherein patternsare formed is folded. Such folded form is photocopied as it has shaped,and a distinctive difference rendered according to the space and colorbetween the shapes is employed. The method using special pattern such asduplication prevention figure, etc. is recently emerged and a uniqueforgery prevention method.

[0018] A micro-printing(also referred to as ‘micro-lettering’) is amethod involving the size of characters or figures to be at leastcertain level when the halftone dots are selected by color or white andblack photocopier. Such method will result in a spoiled original form ofcharacters or shapes when the characters or shapes are printed out atthe lower level by a color photocopier.

[0019] A method of matching front/back copy concerns a preventive methodagainst duplicate print of the front/back sides by a forger forging thedesign. When photocopying twice for forgery, matching accurately theprint out of the front side with the print out of the back side is avery difficult task for an ordinary technique. By applying the method ofmatching front/back sides, it is possible to prevent forgery of forgingtwice with the front and back sides.

[0020] The above-mentioned design methods play a big role in preventingthe forgery/alteration of the securities. Forgery/alteration by anordinary user without special device is fundamentally impossible.

[0021] 3. Method Using Special Ink

[0022] A method using special ink includes a conventionally usedfluorescence method, a method using ink for convexo-concave print, amethod using metal ink (gold powder, silver powder, etc.), and a methodusing thermographical discoloration ink, unchangeable ink and chemicalreactive ink, etc.

[0023] The fluorescent method involves a fluorescent phenomenonoccurring from a mixture of fluorescent material and ink at the exposureof ultraviolet light, which is not visible by naked eye, butdistinguishable only by ultraviolet light. This method is the mostuniversally used forgery prevention technique at present times. Since itis not distinguishable by print-outs, its forgery prevention effect isvery excellent. Its original use is intended for examining whether thereis crack after welding the joints of the highly precision machine suchas ships or spaceships, etc., but now it is applied in printing. Theeffect thereof is very good when simultaneously using both as it isvisible by naked eye and it involves fluorescent ink.

[0024] 4. Special Print Method

[0025] A special print method involves an integral printing, rainbowprinting, negative printing, bar code printing, OCR, and MICR numberingprinting, etc.

[0026] The integral printing is not a printing process of the general PSplate or of baking the film on a flat plate, but of corroding stainlesscopper plate, printing in ultraviolet ink, and drying by passing throughultraviolet light. When the surface is examined, a jaggedconvexo-concave phenomenon appears on the paper surface. Similarlyimitating, a similar effect may be obtained by completing the printingbefore making the copper plate, and making convexo-concave bycompressing with platon or press.

[0027] The rainbow printing is a process of printing each of severalportions of parts made of a film or a plate in different colors,respectively. Such process involves removing a vibration rollerinstalled for the purpose of blending the ink well among the machineryrollers, blocking the spot where the ink is distributed according todifferent colors, and letting the ink poured down as it is in a straightline.

[0028] The negative printing is accomplished by number of linesrepresenting the thickness of between halftone dots when all theprinting is accomplished. The general printing uses 175 lpi (lines perinch), the gift certificate uses at least 200 lpi and the photographuses 1200 lpi. The current printing has been improved to the extent ofusing 1200 lpi. When printing with the angles between halftone dots wellblended to make a pattern shape and to print, it is difficult todistinguish by naked eyes, but when photocopied, only thetwisted/spoiled halftone dots are photocopied so that a patterncompletely different from the original is photocopied.

[0029] The bar code printing is a process printing the previouslyprepared inputted bar codes. The forgery becomes impossible since theforger cannot confirm what content has been inputted.

[0030] In OCR, MICR numbering printing, the numbering itself has beenestablished by encryption which is a special numbering having its ownchecking system. OCR detects with light, and recognizes magnesiumblended in MICRDMS ink as magnetic material. The forger on the outsidedoes not know the established codes so the forgery is impossible. OCR iswidely used in preventing the forgery and alteration of the stockcertificate, and MICR is a numbering method used for preventing theforgery/alteration of checks.

[0031] The aforementioned methods to prevent the forgery/alteration suchas the method using special paper, the design method, the method usingspecial ink, the method using special print, etc. are based on thesafety of the forgery/alteration prevention methods relying on thespecialty of ink or paper, etc. necessary for making all securities, andthe weakness of the peripheral units such as a printer, a photocopier,etc. themselves.

[0032] Accordingly, the manufacturing cost is relatively expensive, thedetection of forgery/alteration is different from each other in itsdetection devices or methods according to the difference in eachrespective method of use and manufacturing method. Particularly, anassistance from a certain institution when making securities is alwaysnecessary. It is very general that a certain institution monopolizesissuance of securities, otherwise a certain public trust attested by acertain institution is depended upon. Thus, in order to make securitiesapplicable of forgery/alteration prevention techniques, involvement ofseveral numbers of certain institutions is necessary.

[0033] Furthermore, a method for determining the forgery/alteration andan apparatus thereof are not universally accepted. Thus, for ordinaryusers to determine forgery/alteration, a considerable knowledge isrequired and the users should be in possession of a discerning abilitycorresponding thereto.

[0034] Also, recently the securities, etc. are all manufactured bydigital file. However, the digital file made prior to the issuance inthe paper form, in its features, has a problem which makes theauthentication of the original copy impossible due to easyforgery/alteration, and unlimited duplication.

[0035] Accordingly, it is impossible to issue securities, etc. only bydigital file itself.

SUMMARY OF THE INVENTION

[0036] In order to simultaneously solve the problems existing in each ofthe aforementioned complicated conventional forgery/alterationprevention methods using special paper, special design, special ink,special printing, etc. and the problem of impossibility inauthenticating the original copy regarding the digital file, the presentinvention has an object to provide method and apparatus for issuingsecurities, etc. in digital file form as it is without any complicatedprocess on user's behalf, and printing them out for their actual use.

[0037] In other words, the present invention sets its object onproviding method and apparatus for issuing securities, etc. usingdigital watermarking wherein the watermark is embedded in thesecurities, etc. in a digital file form for authenticating the originalcopy, and such watermark-embedded securities, etc. are issued easily andsafely on-line, or after the purchase and being printed out from theprinter, the print outs in the paper form are immediately usableoff-line as securities, etc.

[0038] Furthermore, the present invention tries to, as its object,provide method and apparatus for authenticating securities, etc. usingdigital watermarking wherein the determination of the forgery/alterationof the issued print outs in the paper form through off-linephotocopying, etc. can be accurately and easily determined by thedetection of the embedded watermark, and authenticated thereof.

[0039] That is, the present invention understands that thecharacteristics of digital file (digital document, image, etc.) bears aproblem wherein the authentication of the original copy is impossibledue to forgery/alteration and unlimited duplication. Thus, as thesecurities, etc. cannot be issued or purchased in the digital file form,the present invention aims as its object to provide apparatus and methodfor issuing and authenticating securities, etc. by using digitalwatermarking which can fundamentally prevent the illegal use ofduplication copies. Such object allows the user to easily and safely getthe securities, etc. issued or to purchase them on-line by applying thedigital watermarking technique which makes the authentication of theoriginal copy possible. After printing them out from the printer, theuser is able to use them as securities, etc. in off-line state, and isable to determine accurately and easily the print outs (print-out copy)from the printer and the duplication copy (photocopied copy) from thephotocopier when printing out the securities, etc. in the digital fileform from the printer and using them off-line.

[0040] In order to achieve the above objects, the present inventionprovides a method for issuing securities etc. in printed-out form to auser, the method comprising the steps of (a) generating a digital fileof said securities etc. and watermark according to an issuance-optionwhich said user has selected; (b) embedding said generated watermarkinto said digital file of said securities etc.; and (c) printing outsaid watermark-embedded digital file.

[0041] It is also desirable that said method further comprise, beforesaid step (a), a step of (a′) connecting said user to a site whichprovides a service for issuing said securities etc. through a networkand selecting an issuance-option.

[0042] It is also desirable that said watermark is generated in step (a)by using at least one of a key-type method, a logo-type method and amethod simultaneously employing both methods.

[0043] It is also desirable that said generating watermark using akey-type method comprises, at least one of generating said watermark bya plurality of keys in accordance with primary information of saidsecurities etc. or generating the watermark using a checksum orhash-value obtained from the entire information of said securities etc.

[0044] It is also desirable that said embedding said watermark at saidstep (b) comprises, at least one of embedding a robust watermark and afragile watermark simultaneously, and embedding a semi-watermark intosaid digital file.

[0045] It is also desirable that said fragile watermark and saidsemi-watermark are embedded with a controlled embedding level such thatsaid printed-out securities etc. are detected only when said securitieshave experienced the first A/D conversion through a scanner, and saidprinted-out securities not being detected when said securities haveexperienced later A/D or D/A conversion.

[0046] It is also desirable that said step (c) comprises the steps of:(c1) adding an option for controlling printing of saidwatermark-embedded digital file; and (c2) printing out saidwatermark-embedded digital file according to said option for controllingprinting.

[0047] It is also desirable that said option for controlling printing atsaid step (c1) comprises an option for setting the number of print outsof said watermark-embedded digital file.

[0048] It is also desirable that said option for controlling printingfurther comprises, in the state of setting said number of print outs, anoption for commanding a memory to delete the latest documentsimultaneously with an end of printing command after the printingcommand has been executed.

[0049] Furthermore, it is desirable that the above option forcontrolling printing at said step (c1) comprises, an option fordisplaying only an information of said securities etc. to be issued oronly an image of securities etc. without watermark embedded thereto on ascreen of the user's terminal when said watermark-embedded digital fileis printed out.

[0050] In order to achieve the other object of the present invention,the present invention provides an apparatus for issuing securities etc.in printed-out form to a user, the apparatus comprising: an issuingmeans for issuing securities etc. in the form of digital file; aterminal being connected with said issuing means through a network,transmitting an issuance-option by selection of said user of securitiesetc. to said issuing means, and receiving securities etc. according tosaid issuance-option from said issuing means; and print-out means beingconnected with said terminal, printing out said securities etc. receivedfrom said terminal, wherein said issuing means comprises: means forgenerating a digital file of said securities, etc. and watermarkaccording to said issuance-option, and means for embedding saidgenerated watermark into said digital file of said securities etc.

[0051] In order to achieve another object of the present invention, thepresent invention provides a method for authenticatingwatermark-embedded securities etc. in the printed-out form, the methodcomprising the steps of: (d) reading said watermark-embedded securitiesetc. in the printed-out form and converting said securities etc. to adigitalized image; (e) extracting watermark embedded at an issuanceapparatus from said digitalized image; (f) generating watermark from aninformation included in said digitalized image; and (g) determiningauthenticity of said securities etc. by calculating a correlationbetween said extracted watermark and said generated watermark.

[0052] It is desirable that the said step (g) comprises the steps of:(g1) calculating a correlation between the extracted robust watermarkand the generated robust watermark; and (g2) calculating a correlationbetween extracted fragile watermark and generated fragile watermark, andthe determination of the authenticity of said securities, etc. is madebased on whether the correlation calculation between said robustwatermarks and between said fragile watermarks satisfies a predeterminedcorrelation condition.

[0053] It is also desirable that said step (g) comprises a step of:calculating a correlation between the extracted semi-watermark and thegenerated semi-watermark, and the determination of the authenticity ofsaid securities, etc. is made based on whether the correlationcalculation between said robust watermarks and between said fragilewatermarks satisfies a predetermined correlation condition.

[0054] In order to achieve still another object of the presentinvention, the present invention provides an apparatus forauthenticating watermark-embedded securities etc. in the printed-outform, the apparatus comprising:

[0055] an image A/D converter for reading said watermark-embeddedsecurities etc. in the printed-out form and converting said securitiesetc. to a digitalized image; and an authenticating unit for extracting awatermark embedded at an issuance apparatus from said digitalized image,generating a watermark from an information included in said digitalizedimage, and determining authenticity of said securities etc. bycalculating a correlation between said extracted watermark and saidgenerated watermark.

BRIEF DESCRIPTION OF THE DRAWINGS

[0056]FIG. 1 is a block diagram illustrating the apparatus for issuingsecurities, etc. using digital watermarking according to the embodimentof the present invention.

[0057]FIG. 2 is a drawing exemplary showing the kinds and shapes of thesecurities, etc. issued from the issuing apparatus of FIG. 1.

[0058]FIG. 3 is a flowchart illustrating the process of issuingsecurities, etc. from the issuing apparatus of FIG. 1.

[0059]FIG. 4 is a drawing representing each of the cases classifiedaccordingly wherein the information determined by kinds and features ofthe securities, etc. issued from the issuing apparatus of FIG. 1 isgenerated as watermark by a key-type method and by a logo-type method,and is embedded in the digital file.

[0060]FIG. 5 is a flow chart representing a process of embeddinginformation determined by kinds and features of the securities, etc.issued from the issuing apparatus of FIG. 1 as a watermark by a key-typemethod.

[0061]FIG. 6a is a drawing showing the selection of the embeddingsection when using DCT and DFT at the frequency domain during theprocess of embedding watermark by key-type method in FIG. 5, and FIG. 6bis a drawing showing the selection of the embedding section when usingDWT at the frequency domain during the process of embedding watermark bykey-type method in FIG. 5.

[0062]FIG. 7 is a flowchart representing a process of embeddinginformation determined by kinds and features of the securities, etc.issued from the securities, etc. issuing apparatus of FIG. 1 as awatermark by a logo-type method.

[0063]FIG. 8 is a drawing specifically representing a step (S35) addingan option for controlling the print outs from the printer in the flowchart of FIG. 3.

[0064]FIG. 9 is a block diagram illustrating an authenticating apparatusof the securities, etc. using digital watermarking according to theembodiment of the present invention.

[0065]FIG. 10 is a flow chart illustrating a process of authenticatingthe securities, etc. from the authenticating apparatus of FIG. 9.

[0066]FIG. 11a is a drawing showing the experiment result of thecorrelation analysis between the robust watermark extracted from thedigitalized image which has undergone various external modificationprocess and the robust watermark generated from the characterinformation of the digitalized image in the authenticating apparatus ofFIG. 9.

[0067]FIG. 11b is a drawing showing the experiment result of thecorrelation analysis between the fragile watermark extracted from thedigitalized image which has undergone various external modificationprocess and the fragile watermark generated from the characterinformation of the digitalized image in the authenticating apparatus ofFIG. 9.

[0068]FIG. 11c is a drawing showing the experiment result of thecorrelation analysis between the semi-watermark extracted from thedigitalized image which has undergone various external modificationprocess and the semi-watermark generated from the character informationof the digitalized image in the authenticating apparatus of FIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0069] Hereinbelow, the preferable embodiments of the present inventionis set forth in details in reference to the attached drawings.

[0070]FIG. 1 is a block diagram illustrating the apparatus for issuingsecurities, etc. using digital watermarking according to the embodimentof the present invention.

[0071] Referring to FIG.1, the issuing apparatus of the presentinvention comprises an issuing means 110 for issuing securities, etc., aplurality of terminals 120 being connected with the issuing means 110through a network, and print-out means 130 being connected with each ofthe terminals 120 respectively, printing out the securities, etc. in thepaper form.

[0072] The issuing means 110 comprises a digital file generator 111, awatermark generator 112, a watermark embedder 113, and a digital filegenerator for print-out 114.

[0073] The digital file generator 111 generates a digital file of therelevant securities, etc. according to the issuance-option selected byuser from the terminal 120.

[0074] The watermark generator 112 generates watermark according to theissuance-option selected by user from the terminal 120, and suchwatermark is generated according to the above issuance-option by usingat least one of a key-type method, a logo-type method, and a methodsimultaneously employing both methods.

[0075] The watermark by a key-type method may be identically defined asthe key used in encryption in which a certain key is given and pseudorandom numbers generated from the key is embedded as watermark. In thisregard, the key may be a specific number or text only known to a personwho generates it, and the key will be used at the later stage forextracting the watermark. In other words, under the assumption that thesecretly embedded watermark is a code, the key is deemed to be a clue todecode such code.

[0076] The watermark by a logo-type method uses a series of images suchas logo as watermark. The image data also can be represented in a seriesof digital signals. Thus, when embedding image data such as logorepresenting the issuer of the original data as watermark, awatermarking method which provides a more visual information than atextraction is available.

[0077] The watermark embedder 113 embeds watermark generated from thewatermark generator 112 in the digital file generated from the digitalfile generator 111, wherein the robust watermark and the fragilewatermark are simultaneously embedded in the above digital file orsemi-watermark is embedded.

[0078] Generally, watermarking methods include, according to theembedding level (level the watermark is embedded) of signals bearing aseries of information, a method for embedding a robust watermarksurviving lo without disappearing against any external attack ormodification or a method for embedding a fragile watermark easilymodified at a minor external attack.

[0079] The method for embedding a robust watermark against the externalattack maintains the information bearing the embedded signals as it isas the robust watermark survives without disappearing against variouskinds of feasible external attacks. Such information includes therelevant information inclusive of the source regarding the securities,etc., and by confirming such information from the extraction of thewatermark, a role authenticating the securities, etc. and distinguishingthereof from the forged/altered copies is to be assumed.

[0080] The method for embedding a fragile watermark against the externalattack can accurately determine whether the make-up offorgery/alteration has been externally made by letting the watermark bedamaged against a minor external make-ups. Accordingly, such methodplays a role that makes the illegal use of the forged/alteredsecurities, etc. impossible.

[0081] Other than employing the above mentioned method for embedding arobust watermark surviving against the external attack and a fragilewatermark susceptible to attack, there is a method of semi-watermarking.The semi-watermarking method embeds a single watermark, however itsattribute is not determined. It can be used as a robust watermark or afragile watermark depending on an environment it is used such asexternal attack, conversion, etc.

[0082] The strength of the watermark has a close relationship with thekind of the external attack. The present invention classifies, dependingon the strength regarding AID conversion or D/A conversion such asmainly the printer's print outs, a hard copy (photocopying by aphotocopier), etc., a robust watermark, a fragile watermark, and asemi-watermark in which a single watermark can be used as a robustwatermark and a fragile watermark according to its application(hereinafter, the classification according to the strength isclassification according to the A/D conversion or D/A conversion).

[0083] The watermarking method applied to the present invention isdivided into a key-type method watermark and a logo-type methodwatermark depending on the methods of generating watermark. It ispossible to embed a robust watermark, a fragile watermark or asemi-watermark with a key-type method watermark. The logo-type methodwatermark can also embed a robust watermark, a fragile watermark or asemi-watermark.

[0084] The watermark embedder 113 controls the embedding level so thatonly in a case only where the watermark-embedded securities, etc. thathave been printed in the paper form, and then have undergone the firstA/D conversion by scanner, etc. are detected when embedding the fragilewatermark or the above semi-watermark in the digital file, but in a casewhere the subsequent A/D or D/A conversion has been made, thewatermark-embedded securities, etc. are not detected.

[0085] It may be possible to forge/alter by making a duplication copywith the print-outs of printer using peripheral units such as aphotocopier or a scanner, etc. In such case, all securities, etc.printed out in the paper form were made into digital image by using ascanner, etc. again in accordance with the authenticating method setforth in the description made below, and undergoes a series of processconfirming the watermark embedded from the above digital image

[0086] In this connection, as for a duplication copy by the photocopier,the robust watermark survives and is extracted. However, the fragilewatermark or the semi-watermark is damaged by the external data loss dueto photocopying, etc. The watermark of the copy scanned by a scanner isalso damaged likewise so that the circulation of the illegal securities,etc. is originally uprooted and blockaded.

[0087] Accordingly, of the present invention, only the securities, etc.in the form of paper printed out from the original copy of the digitalfile satisfy the result of the extraction of the fragile watermark orthe semi-watermark. In other words, the primary characteristic of thepresent invention lies in the controlling of the embedding level of thewatermark so that only when the image of the securities, etc. in theform of paper is converted to the digital form for the first time (forexample, scanning for authentication), the fragile watermark or thesemi-watermark is to be detected, and after undergoing the subsequentA/D conversion or D/A conversion through scanner, photocopier, printer,etc., the fragile watermark or the semi-watermark is not to be detected.

[0088] The digital file generator for print-out 114 provides an optionfor controlling the print out means 130 in order to prevent the printingthe identical issued copy out and using it freely according to itsissuance option when the watermark-embedded digital file out of thewatermark embedder 113 is issued on-line and printed out in the paperform.

[0089] In other words, when the watermark-embedded digital file isprinted out in the paper form from the above print-out means 130, anoption for setting arbitrarily the number of print-outs can be added.Or, after executing the print-out command in a state wherein the numberof print-outs is set, an option for commanding to delete the latestdocument in the memory of the terminal simultaneously with the end ofthe print-out command.

[0090] Or, when the water-mark embedded digital file is printed out inthe paper form from the print-out means 130, an option for establishingeither a display of the information only which confirms the content ofthe securities, etc. to be issued on the screen of the above terminal ora display of the images only of the securities, etc. which do not embedwatermark thereto can be added.

[0091] The terminal 120 is connected with issuing means 110 through thenetwork, and furthermore, the issuance-option of the securities, etc.which are sought to be issued through the terminal 120 is selected andtransferred to the above issuing means 110. Also, the terminal 120receives the securities, etc. according to the above issuance option andgets them printed out in the paper form through the print-out means 130.

[0092] The terminal 120, for example, may be Personal Computer (PC),Personal Digital Assistants (PDA), etc. which are connected to a networksuch as internet and exchanges the data with the issuing means on-line.The terminal 120 is connected with the print-out means 130 by wire orwireless transmission, and get the securities, etc. issued, for example,through a printer.

[0093]FIG. 2 is a drawing exemplary showing the kinds and shapes of thesecurities, etc. issued from the issuing apparatus of FIG. 1. Thesecurities, etc. applicable to the present invention include theconventional types of securities such as gift certificate, various kindsof tickets, coupon, electronic stamp, bond & debenture, note, stockcertificate, lottery, paper money, check, etc. in a digitalized fileform, and various public documents being issued requiring confirmationand authentication.

[0094] The present invention can utilize the design used in theconventional securities, etc. again, and by embedding watermark thereto,the issuance and circulation of the above conventional securities, etc.can be actively bloomed by a more convenient method.

[0095]FIG. 3 is a flowchart illustrating the process of issuingsecurities, etc. from the issuing apparatus of FIG. 1. Referring to FIG.3, the process of issuing the securities, etc. in accordance with theembodiment of the present invention is explained hereinbelow.

[0096] First, the user connects with issuance service for the relevantsecurities, etc. which he/she wishes to get issued through network(S31), and selects an issuance option of the relevant securities, etc.(S32).

[0097] The above securities, etc. issuance service may be devices suchas issuers of the securities, etc., homepage, web server or kiosk of thesecurities, etc. issuers. Also, the servers connected with user arerespectively different according to the difference in each of thesecurities, etc. desired by user.

[0098] The user connects with the issuer from which he/she wants to getthe desired securities, etc. issued and selects the option necessary forthe securities, etc. to be issued. At this moment, the user selects thenecessary information. For example, in a case of electronic stamps,there are an option for selecting express mail or registered mail orordinary mail for the postal matters to be sent, an option for selectingprice according to the weight of the post matters, and an option forselecting the design of the electronic stamp, etc. In a case of giftcertificates, there are an option for selecting kinds of giftcertificates such as fitness gift certificate, oil and gas certificate,book gift certificate, merchandise gift certificate, merchant specificgift certificate, etc., an option for selecting price of the giftcertificates, and an option for selecting the term of validity, etc.

[0099] In a case of securities, an option regarding the face value, anoption for term of validity, and an option regarding information on theissuer's agencies concerned, etc. are being selected. According to theabove user's selection, the kinds and features of the securities aredetermined.

[0100] According to the issuance option selected in the above, thedigital file and watermark of the relevant securities, etc. aregenerated (S33)

[0101] When the kinds and features of the above securities, etc. aredetermined, the digital file of the pertinent securities, etc. basedthereon is generated, and also, the watermark to be embedded into suchdigital file is generated.

[0102]FIG. 4 is a drawing representing each of the cases classifiedaccordingly wherein the information determined by kinds and features ofthe securities, etc. issued from the issuing apparatus of FIG. 1 isgenerated as watermark by a key-type method and by a logo-type method,and is embedded in the digital file.

[0103] The information embedded as watermark becomes a very importantinformation necessary for protection or confirmation regarding thesecurities, etc. selected by user. That is, such information is made ofprice information, issuance-related information, term of validityinformation, and information on user who got issued, etc.

[0104] The information of the watermark to be embedded which isdetermined by kinds and features of the securities, etc. includes thefollowing information.

[0105] First, information of the issuing country or issuer is included.Securities, etc. such as electronic stamps or government issuing bondsrequire information on issuing countries. For stock certificates or giftcertificates, issuer information is included. As for gift certificatesissued from the department stores, information specifying the pertinentdepartment stores is included.

[0106] Secondly, the par value is included. Electronic stamps, giftcertificates, stock certificates, bond & debentures, notes, etc. includepar values as values of all securities. For example, in case ofelectronic stamps, price is divided into 170 Won, 250 Won, etc. and incase of gift certificates, they are divided into a fifty-thousand Wongift certificate, a hundred-thousand Won gift certificate, etc. (Won isrefers to a monetary Unit in the Korea) In case of stock certificates,each stock certificate will be different from each other according tothe issuers wherein the stock certificates are divided into afive-thousand Won stock certificate, etc.

[0107] Third, the issuance year of the securities, etc. is included.Almost all securities, etc. include the issuance year.. The relationbetween issuance year and face value of securities such as bond &debentures or notes are more important.

[0108] Fourth, the term of validity of the securities, etc. is included.The term of validity of the notes or bond & debentures is closelyrelated to their values. Particularly, for notes, authenticationregarding the term of validity is an indispensable factor.

[0109] Fifth, securities, etc. will additionally include extrainformation according to their own needs other than the above describedfour information. Securities, etc. such as entrance tickets or usertickets include information such as subjects, place, designated number,etc. necessary for the relevant securities.

[0110] Sixth, check-sum value or hash value, etc. regarding informationon securities in order to determine the forgery of all information inthe securities, etc. can be included as a key information for generatingwatermark signals. For instance, new value, i.e. check-sum value or hashvalue using the above user information are generated. In other words,the check-sum value or hash value generate a certain length of databased on the existing information, which do not conform to the check-sumvalue or hash value when portion of the existing information has beenchanged.

[0111] Information embedded as watermark in the securities, etc. isgenerated based on the basic information included in such securities.According to the technical factors of the embedding watermark, watermarkusing a key-type method watermark, a logo-type method watermark, orwatermark using both key-type method and logo-type method are generatedbased on the above watermark information to be embedded, and embeddedinto the securities, etc. of the existing digital file type.

[0112] Embedding watermark is classified into a case of simultaneouslyembedding robust watermark and fragile watermark, and a case ofembedding a semi-watermark. When simultaneously embedding robustwatermark and fragile watermark, the robust watermark by a logo-typemethod or a key-type method generated from the above information of thesecurities, etc. and a fragile watermark by a logo-type method or akey-type method are embedded concurrently in the digital file, and basedon the embedded watermark information, legality of the securities, etc.are determined later.

[0113] A circumstance wherein information to be embedded in saidsecurities, etc. is embedded with watermark generated by a key-typemethod and a circumstance wherein the watermark is generated by alogo-type method are explained as follows.

[0114] First, a key-type method illustrated on the left side of FIG. 4is explained.

[0115] In a key-type method, a key is generated based on the informationto be embedded. That is, a key for generating a signal to be embeddedinto securities, etc. in the form of digital file is generated based onthe information that is included in securities, etc.

[0116] The process of generating a key is explained by taking anexample, e.g., in case where the embedded information is an issuingcountry—KOREA (BG refers to information on an issuing country, BH refersto information on an issuing company or an issuer) as follows:

[0117] (1) Int(BG) step: A code sequence is generated based on thewatermark information, i.e., an issuing country—KOREA, to be embedded bythe information of securities. That is, change of a character-formedvariable into the ASCII code value results in a sequence of number. Forexample, a character is changed into k 75, etc. according to the ASCIIcode table.

[0118] (2) K(Int(BG)) step: The generated number sequence becomes a keyof generating a signal to be embedded as a watermark (the generatednumber sequence of ASCII code=random number generating key=seed value).

[0119] (3) R(K(Int(BG))) step: A random number sequence is generated bythe key generated in said step (2). There are various methods ingenerating a random number by a decimal sequence in which a seed numbermethod is most frequently used. That is, a random number is generated bymaking the key generated in said step (2) as one seed number. After all,R(K(Int(BG))) itself, a sequence comprising the generated random number,becomes a watermark to be embedded as a signal including information.

[0120] R(K(Int(V))) in the left side of FIG. 4 is a random numbersequence generated by the par value of securities, R(K(Int(D1))) israndom number sequence generated by the issuing year of securities, andR(K(Int(D2))) is a random number sequence by the term of validity.Finally, R(K(Int(W))) is a random number sequence generated by otherinformation of securities. The generated random number sequence as aboveis embedded as a watermark. Upon detecting watermark, a key is generatedbased on the information of securities, etc. and a random numbersequence is generated by the generated key in the same manner asdescribed above. Further, authenticity of securities, etc. is determinedby means of a method of calculating correlation between the randomnumber sequence generated by the information of securities, etc. and thesequence extracted from watermark which is embedded into securities,etc.

[0121] Next, a logo-type method illustrated in the right side of FIG. 4is explained.

[0122] A logo-type method means that information which is included insecurities, etc. is generated as a watermark as it is and then embedded;that is, it is embedded by imaging the information to be embedded. Forexample, the information that is included in securities, etc., i.e.,issuing country—KOREA, price—50000 Won, term of validity—2000. 12. 31,is imaged as they are and then embedded.

[0123]FIG. 5 is a flow chart representing a process of embeddinginformation determined by kinds and features of the securities, etc.issued from the issuing apparatus of FIG. 1 as a watermark by a key-typemethod.

[0124] A key-type method is based on detection of which core lies indetection. A step of generating a key is first explained and then a stepof embedding a watermark into securities, etc. is explained.

[0125] A step of generating a key comprises the steps of analyzingsecurities, etc., selecting a key point, generating a random signal.Through said three steps, a key being used is selected and a signal isgenerated by the key. Selection of a key being used is executed in thestep of selecting a key point.

[0126] Said step of generating a key employs a part of information ofsecurities, etc. as various keys or a checksum value or a hash valuerelating to the entire information of securities, etc, as a key.

[0127] Specifically, in case where both text-formed information andimage-formed information coexist in securities, etc. themselves, thereare various methods including a method of selecting a key by applying acertain rules to the existing text, a method of selecting a key based onthe information to be input so as to issue securities, etc. byconnecting a user to a main server, and a method of selecting a keybased on price, date, connecting time and the like of securities, etc.to be issued.

[0128] For example, in case where both text-formed information andimage-formed information coexist in securities, etc. themselves, thereare many methods, e.g. characters from 5^(th) to 9^(th) are employed asa key, five characters from the first appearing character ‘A’, in thedocument are employed as a key, if the price of securities, etc. is10000 Won, the price itself is employed as a key.

[0129] Meanwhile, the information which is actually embedded is not akey but a signal (random number sequence as mentioned above) generatedby the key. Using a key generated in said step of selecting a key pointleads to generating such signal.

[0130] There are various methods in generating a signal to be embedded.For example, a method of employing a key itself as a signal, a method ofembedding a signal generated by encrypting already known text documentusing a key as a secrete key of the designated document, a method ofmaking a key as a seed number and generating a random signal and takinga part thereof, and a method of preparing and embedding a signal pairedwith the key using a specific function.

[0131] As such, a random signal related to the key is generated aftergoing through three sub-steps of the step of generating a key. Herein ifa key is defined as k and a signal generated by the key and thenembedded is defined as S(k), the image of security (image which isincluded in securities, etc. or image of security itself) goes throughthe steps of image blocking, zigzag scan, domain transform, analysis ofcoefficient, and selection of the embedding section, which are thepre-processing steps for embedding the signal S(k).

[0132] First, in the step of image blocking, the existing image ofsecurities, etc. are divided into a block. Images are usually dividedinto the form of 8×8, 16×16, 32×32. In this regard, since the form ofimage of securities, etc. differs depending on the issuer or type ofsecurities, etc., said division is necessary for applying to a varietyof forms in the image, which has a close relation with strength of asignal to be embedded.

[0133] Next, the step of zigzag scan is a process for convertingtwo-dimensional image data into one-dimensional image. Raster scan orHilbert scan and the like are employed other than said zigzag scan.

[0134] Next, in the step of domain transform, a domain of the data fromsaid zigzag scan is transformed using a mathematical transform. Thereare DFT, DCT, DWT, etc. in a mathematical transform being used.

[0135] Next, the step of analyzing a coefficient determines a section ofselection. In case of proceeding with transform such as DFT, DCT, andDWT, the processing of embedding a watermark is made in a frequencydomain. The transformed data is divided into a low-frequency componentand high-frequency component wherein high-frequency component largelydisappears in applying algorithm like compression, whereas low-frequencycomponent is not suitable for embedding a signal since even its minorchange largely affects on the entire image. Thus, finding out a sectionfor embedding a watermark and deciding to embed a signal in which forminto the section in the low-frequency component are important inapplying algorithm.

[0136] Next, the step of selecting the embedding section selects asection into which watermark is embedded. Selection of the embeddingsection has a close relation with the mathematical transform employed.

[0137] Said domain transform includes a discrete cosine transform (DCT),discrete fourier transform (DFT), discrete wavelet transform (DWT), etc.Using these methods results in transforming a domain into a frequencydomain. In selecting a section for embedding a watermark, a method ofembedding a watermark into middle- or low-frequency area is shown inFIG. 6a and FIG. 6b.

[0138] In case of employing DCT or DFT, a section of embedding thesignal S(k) is shown as FIG. 6a which is specifically explained later.In case of employing DWT, its embedding section is shown in the form ofblock as FIG. 6b which is specifically explained later.

[0139] As described above, after generating a watermark to be embedded,said generated watermark is embedded into said selected embeddingsection of the digital file of said corresponding securities, etc.

[0140] A fragile watermark is first embedded into said digital file andthen a robust watermark is embedded. If a semi-watermarking is applied,a semi-watermark is embedded regardless of the order. Embedding saidgenerated watermark into securities, etc. makes said watermark-embeddedsecurities, etc. into securities, etc. with their issuance or purchaseavailable.

[0141] It could be said that the process of embedding the generatedwatermark based on the information from kinds and features of saidsecurities, etc. into a digital file indicates the process of embeddingthe signal S(k) generated by a signal key into the digital file ofsecurities, etc. generated through said pre-processing steps. In case ofembedding said S(k) into digital file as it is, since the image ofsecurities, etc. is changed, a correlation coefficient a is employed inembedding the S(k). The embedding process is expressed as the followingmathematical formula 1. [Mathematical Formula 1]

W′(u)=W(u)+α·S(k)

[0142] Herein, W′(u) refers to data of the watermarked security data,W(u) refers to data of the original security, α refers to a parameternecessary for controlling strength of the signal data S(k) to beembedded and data of the original security. A process of embedding awatermark expressed as said mathematical formula 1 is more specificallyexplained.

[0143] The present invention suggests new methods to decide the propertyof watermark in embedding a watermark. In particular, the presentinvention suggests a watermarking method capable of off-line detecting(as a result of printing, a watermark is detected in a printing-out inthe form of paper and the printing-out in the form of paper isauthenticated) so as to detect a watermark in state of printed-out. Itsspecific content is explained referring to FIG. 6a and FIG. 6b.

[0144]FIG. 6a is a drawing showing the selection of the embeddingsection when using DCT and DFT at the frequency domain during theprocess of embedding watermark by key-type method in FIG. 5, and FIG. 6bis a drawing showing the selection of the embedding section when usingDWT at the frequency domain during the process of embedding watermark bykey-type method in FIG. 5

[0145] The selection of the embedding section using DCT and DFT areillustrated with reference to FIG. 6a, and that of using DWT isillustrated with reference to FIG. 6b.

[0146] A method of embedding a watermark with reference to FIG. 6a isexplained hereinbelow.

[0147] If each converted DCT coefficient is Ci, it is K<Ci<R (K, R>0).Under such condition, there are two methods of embedding a watermark.The range of data applying said two methods is indicated as theembedding section of DCT and DFT in FIG. 6a. The first is a method bythe replacement and the second is a method by the summation (+). Beforeexecuting such two methods, the identical coefficient, which is Ci=Pi,is set.

[0148] Firstly, in a method by the replacement, in case where it is−1<Ci<1, it is set as Wmi=Pi (Wmi refers to a watermark coefficient).

[0149] Secondly, in a method by the total, in case where it is Ci<−1,Ci>1, it is set as Ci=Ci+α|P_(i)| Wmi wherein α is a coefficient ofcontrolling the embedding strength.

[0150] If a watermark is embedded by said embedding method, although awatermark is illegally generated due to the disclosure of key value orrandom sequence, such illegally generated watermark fails to be detectedif the embedding method is not identical to as described.

[0151] In FIG. 6b, the part indicated by an arrow is the DWT embeddingsection. Like FIG. 6a, a method of embedding a watermark is able toapply both method by the replacement and method by the summation (+)whose explanation is the same as that of FIG. 6a.

[0152]FIG. 7 is a flowchart representing a process of embeddinginformation determined by kinds and features of the securities, etc.issued from the securities, etc. issuing apparatus of FIG. 1 as awatermark by a logo-type method.

[0153] An embedding process of logo-type method is almost the same asthose of key-type method, except that a signal to be embedded isdifferent from that of a key-type method. That is, said two embeddingmethods explained with reference to said FIG. 6a are applied to alogo-type method.

[0154] The signal to be embedded in the logo-type method is prepared onthe basis of an image form or text form. First in the step of preparingthe embedding logo in FIG. 7, a logo to be embedded is prepared on thebasis of securities, etc. At this time, a logo to be embedded is made toinclude information necessary for securities, etc. The logo conversionstep executes a specific conversion in order to maintain thecharacteristics of a watermark such as robustness or fragility afterembedding. For example, in case where a logo is a monochromatic image, amethod of changing the range of quantization, etc. belongs to a logoconversion. Subsequently, a domain transform is executed. Otherremaining process is the same as that of the key method explained withreference to FIG. 5.

[0155] Further, there is employed a method in combination with saidlogo-type method and said key-type method. Such method makes it possibleto determine whether securities, etc. are forged or altered incomparison with information of securities, etc. extracted by a logo-typemethod and logo information initially embedded or, whether securities,etc. are forged or altered and photocopied in comparison withinformation of securities, etc. extracted by a key-type method andinformation initially embedded as a key.

[0156] In contrary, such method enables to determine whether securities,etc. are forged or altered in comparison with information of securities,etc. extracted by a key-type method and information initially embeddedas a key or, whether securities, etc. are forged or altered andphotocopied in comparison with information of securities, etc. extractedby a logo-type method and logo information initially embedded.

[0157] Referring back to FIG. 3, when watermark embedded securities,etc. in the form of digital file in the step of S34 are transmitted to auser through a network by adding an option for controlling printing(S35), the user prints out a watermark-embedded digital file accordingto the option for controlling printing (S36).

[0158]FIG. 8 is a block diagram specifically representing a step (S35)adding an option for controlling printing in FIG. 3.

[0159] Since said securities, etc. are available immediately after beingprinted-out by a user, the user should go through the step (S35) ofcontrolling printing, which prevents watermark-embedded securities, etc.from being printed-out several sheets and being used in duplication.

[0160] To be more particular, if a user wants to printout securities,etc., said terminal 120 should satisfy the requirement ofprinting-option. The printing-option provided in the issuing means 110provides an option for controlling setting of the number of print outs,option for controlling memory, and option for controlling screen and thelike.

[0161] First, the option for controlling setting of the number of printouts controls the process of setting the number of print outs ofsecurities, etc., which is identical in the existing setting of printout. The printing-option provided in the issuing means 110 controls soas to set only the number of print outs to meet the requirement ofissuance.

[0162] In other words, the number of print outs is fixed as much as thenumber of sheet for which a person who requests an issuance paid, whichis for the purpose of preventing the identical security from being usedin duplication.

[0163] The option for controlling a memory is to decide the number ofprint outs as much as the number of sheet designated according to theconditions, which is to complete the process in the option forcontrolling setting of the number of print outs.

[0164] If a user is printing, the information related to the printing istemporarily stored in a memory. The user commands a memory to delete thelatest document of memory simultaneously with an end of printing commandafter the printing command has been executed. Thus, the print outthrough second times is completely controlled.

[0165] The option for controlling a screen is to prevent a computerscreen itself from being captured and printed out. For this, variousmethods are employed.

[0166] First, when issuing securities, etc. from the issuing means 110,it is set to print out securities, etc. immediately after a buyerconfirms that the image of ticket itself to be issued is not displayedon a screen and only the information capable of confirming the contentto be issued is displayed.

[0167] There is another method that the image of securities, etc. withno watermark embedded is displayed on a screen whereas, awatermark-embedded image is actually issued.

[0168] As described above, issuance of securities, etc. using a digitalwatermarking of the present invention analyzes the kinds and features ofeach of securities, etc., generates a digital -file and watermark to beembedded into said digital file according to kinds and features thereof,embeds a robust watermark and fragile watermark with a controlledembedding level or a semi-watermark with a controlled embedding levelinto securities, etc. in the form of digital file so as to authenticatethe original of securities, etc. before issuance and purchase, and addsfurther an option for printing out only the designated number of sheet.

[0169] The present invention provides a new method that has latelyattracted attention and is differentiated from the existing varioustechnologies related to the prevention of forgery and alternation. Inparticular, the method of applying a robust watermark and fragilewatermark simultaneously or a semi-watermark only used in the presentinvention is considerably advanced to the existing various technologies,in the methods facing a variety in the technology of forgery andalternation.

[0170] Next, when it comes to using watermark-embedded securities, etc.which are issued through an issuing apparatus, an authenticatingapparatus and method thereof are explained.

[0171]FIG. 9 is a block diagram illustrating an authenticating apparatusof securities, etc. using digital watermarking according to theembodiments of the present invention.

[0172] Referring to FIG. 9, the authenticating apparatus comprises animage A/D converter 210 for reading watermark-embedded securities, etc.in the form of paper and converting them into the image in the form ofdigital, an authenticating unit 220 fof detecting watermark in thedigitalized image in said image A/D converter 210 and determining theauthenticity of the securities, etc., and an authentication resultoutput 230 fof printing out the authentication result in saidauthenticating unit 220.

[0173] The authenticating unit 220 analyzes a correlation between thewatermark extracted from the digitalized image in the image A/Dconverter 210 and the watermark generated from character information ofthe digitalized image and determines the authenticity of the securities,etc.

[0174] In analyzing the correlation in the authenticating unit (220), incase where said extracted and generated watermark are a robust watermarkand fragile watermark, a successful extraction of both watermarksresults in legality of securities, etc., and extraction of either robustwatermark or fragile watermark results in illegality of securities, etc.

[0175] Further, In connection with analysis of the correlation in saidauthenticating unit 220, in case where the extracted and generatedwatermark is a semi-watermark, a successful extraction of saidsemi-watermark results in the legality of securities, etc. and noextraction results in the illegality of securities, etc.

[0176]FIG. 10 is a flowchart illustrating a process of authenticatingthe securities, etc. from the authenticating apparatus of FIG. 9.

[0177] First, a watermark-embedded securities, etc. to be authenticatedin the form of paper is image-digitalized through a scanner (S101). Inthis step, the existing scanner can be employed or it can be convertedinto the digitalized image through a digital camera, etc.

[0178] If the digitalized image of securities, etc. is obtained,watermark which is embedded at said issuing apparatus is extracted fromsaid digitalized image. Said extraction is made, using a characterrecognizing apparatus, by extracting information on the par value,information on the term of validity, information on the issuing personor issuer concerned, etc., which are embedded as a watermark at theissuing apparatus (S102).

[0179] Further, a watermark is generated from the character informationof said digitalized image of securities, etc. (S103). In this regard,the generated watermark a little varies depending on the watermarkingmethod employed in generating a watermark at the issuing apparatus ofthe present invention.

[0180] In case where the watermarking method employed in generating awatermark at the issuing apparatus is a key-type method, since a signal(watermark) to be embedded into securities, etc. is generated by makingthe information included in the digitalized image as a key, a watermarkis generated from the digitalized image by making the information ofcharacter which is included in securities, etc. as a key using a(optical) character recognizing apparatus.

[0181] In extracting and generating watermark in the authenticatingprocess for preventing securities, etc. from being forged and altered,only the image part from which watermark is extracted is extracted. Forexample, in the case of an electronic stamp, there is a process ofextracting only a stamp part from the scanned entire image except theexisting envelope part.

[0182] Such process is to extract a specific part from the obtainedimage like the recognizing apparatus of number plate of vehicle. In thisregard, Korean Patent Application No. 1999-41111 with the same applicantas that of the present invention discloses the above technology indetail.

[0183] The correlation analysis between such extracted and generatedwatermarks is calculated in order to determine the authenticity of thesecurities, etc (S104).

[0184] As a result of analyzing a correlation between said extracted andgenerated robust watermarks (S105), failure to extract a robustwatermark causes to illegality of securities, etc., thereby losing theireffectiveness (S108).

[0185] In said step of S105, if a robust watermark is extracted, bymeans of the correlation analysis between said extracted and generatedfragile watermarks (S106), a successful extraction of a fragilewatermark causes to legality of securities, etc. and thus enables theireffective distribution (S107), failure of such extraction causes toillegality of securities, etc. and enables to lose their effectiveness(S108). In other words, failure to extract a fragile watermark isconsidered confirming that securities, etc. are not original butphotocopy.

[0186] Further, in case where said extracted and generated watermark isa semi-watermark, by means of the correlation analysis, a successfulextraction of a semi-watermark causes to legality of securities, etc.and enables their effective circulation, failure in extraction of asemi-watermark causes to illegality of securities, etc. and enables tolose their effectiveness.

[0187] In case of generating and embedding a watermark in combinationwith a logo-type method and key-type method mentioned above, inconnection with said determining the authenticity of the securities,etc., in case where extracted and generated watermark is a logo-typemethod watermark and key-type method watermark, whether securities, etc.are forged or altered is decided in comparison with information ofsecurities, etc. extracted by a logo-type method and logo informationinitially embedded, and whether securities, etc. are forged or alteredand photocopied is decided in comparison with information of securities,etc. extracted by a key-type method and information initially embeddedas a key.

[0188] With respect to said determining the authenticity of thesecurities, etc., whether securities, etc. are forged or altered isdecided in comparison with information of securities, etc. extracted bya key-type method and information initially embedded as a key andwhether securities, etc. are forged or altered and photocopied isdecided in comparison with information of securities, etc. extracted bya logo-type method and logo information initially embedded.

[0189]FIG. 11a is a drawing showing the experiment result of thecorrelation analysis between the robust watermark extracted from thedigitalized image which has undergone various external modificationprocess and the robust watermark generated from the characterinformation of the digitalized image in the authenticating apparatus ofFIG. 9.

[0190] Robust watermark embedded securities, etc, in the form of papershows the extraction result of robust watermark according to theprocessing each executed as described below.

[0191] 1) Print out→scan : extraction of robust watermark

[0192] 2) Print out→photocopy→scan extraction of robust watermark

[0193] 3) Print out→scan→print out→scan: extraction of robust watermark

[0194] As such, a robust watermark survived an illegal photocopy orillegal scan besides the first print out and the scan forauthentication. That is, said authentication through a robust watermarkdoes not decide the forgery such as illegal photocopy but executes thefunction of deciding the alteration such as change in the face value.Absolutely, if such alteration occurred, there is no extracted robustwatermark.

[0195]FIG. 11b is a drawing showing the experiment result of thecorrelation analysis between the fragile watermark extracted from thedigitalized image which has undergone various external modificationprocess and the fragile watermark generated from the characterinformation of the digitalized image in the authenticating apparatus ofFIG. 9.

[0196] Fragile watermark embedded securities, etc, in the form of papershows the extraction result of a fragile watermark according to theprocessing each executed as described below.

[0197] 1) Print out→scan: extraction of fragile watermark

[0198] 2) Print out→photocopy→scan : no extraction of fragile watermark

[0199] 3) Print out→scan→print out→scan: no extraction of fragilewatermark

[0200] Like said result of 1), both extraction of robust watermark andfragile watermark authenticates that the paper-formed print out is theoriginal and legal securities, etc. Like said results of 2) and 3),although extraction of a robust watermark makes it possible to expectthat the paper-formed print out is the original without alternation, noextraction of a fragile watermark indicates that the paper-formed printout is illegal securities, etc. which are photocopies forged with anundesirable intention.

[0201]FIG. 11c is a drawing showing the experiment result of thecorrelation analysis between the semi-watermark extracted from thedigitalized image which has undergone various external modificationprocess and the semi-watermark generated from the character informationof the digitalized image in the authenticating apparatus of FIG. 9.

[0202] Semi-watermark embedded securities, etc, in the form of papershows the extraction result of a semi-watermark according to theprocessing each executed as described below.

[0203] 1) Print out→scan: extraction of semi-watermark (robust watermarkcharacteristic)

[0204] 2) Print out→photocopy→scan: no extraction of semi-watermark(fragile watermark characteristic)

[0205] 3) Print out→scan→print out→scan: no extraction of semi-watermark(fragile watermark characteristic)

[0206] Like said result of 1), extraction of a semi-watermarkauthenticates that the paper-formed print outs are the original andlegal securities, etc. and like said result of 2) and 3), no extractionof a semi-watermark indicates that they are illegal securities, etc.being photocopied with an undesirable intention.

[0207] Industrial Applicability

[0208] As described above, apparatus and method for issuing andauthenticating securities, etc. using digital watermarking of thepresent invention makes it possible to issue and purchase securities,etc. on-line with the existing design of securities, etc.

[0209] In other words, while a user does not going to an issuer inperson and issuing or purchasing paper-formed securities, etc., the usercan issue or purchase securities, etc. on-line without a limitation oftime or place and use the paper-formed securities, etc. off-line inprinted-out form. Further, when using the issued or purchasedsecurities, etc., it can easily and accurately determine the forgery oralternation thereof employing a simple apparatus.

[0210] Thus, it constitutes a safe and transparent system of circulationof securities, etc. and thus activating the circulation.

[0211] Up to now, although the preferred embodiments of apparatus andmethod for issuing and authenticating securities, etc. using digitalwatermarking of the present invention are disclosed and explained, suchembodiments are merely for illustrations but are not restricted to theillustrations for those skilled in the art.

[0212] That is, with another authentication server, a watermark isembedded and extracted according to the used period and serial number ofsecurities, etc. authenticated in said server, which makes it possibleto prevent illegally photocopied securities, etc. from beingdouble-used, or forged or altered as to the used period. It is obviousthat such can be variously changed, transformed and replaced within thescope of the technical idea of the present invention.

[0213] Further, it should be understood that the technical idea of thepresent invention is not restricted to the aforementioned embodimentsbut to only the claims attached hereto and their equivalent technicalprinciple.

What is claimed is
 1. A method for issuing securities, etc. inprinted-out form to a user, the method comprising the steps of: (a)generating a digital file of said securities, etc. and watermarkaccording to an issuance-option which said user has selected; (b)embedding said generated watermark into said digital file of saidsecurities, etc.; and (c) printing out said watermark-embedded digitalfile.
 2. The method according to claim 1, wherein the method furthercomprises, before said step (a), a step of: (a′) connecting said user toa site which provides a service for issuing said securities, etc.through a network and selecting an issuance-option.
 3. The methodaccording to claim 1, wherein said watermark is generated in step (a) byusing at least one of a key-type method, a logo-type method and a methodsimultaneously employing both methods.
 4. The method according to claim3, wherein said generating watermark using a key-type method comprises,at least one of generating said watermark by a plurality of keys inaccordance with primary information of said securities, etc. andgenerating said watermark using a checksum or hash-value obtained fromthe entire information of said securities, etc.
 5. The method accordingto claim 1, wherein said embedding said watermark at said step (b)comprises, at least one of embedding a robust watermark and a fragilewatermark simultaneously, and embedding a semi-watermark into saiddigital file.
 6. The method according to claim 5, wherein said fragilewatermark and said semi-watermark are embedded with a controlledembedding level such that said printed-out securities, etc. are detectedonly when said securities have experienced the first A/D conversionthrough a scanner, and said printed-out securities not being detectedwhen said securities have experienced later A/D or D/A conversion. 7.The method according to claim 1, wherein said step (c) comprises thesteps of: (c1) adding an option for controlling printing of saidwatermark-embedded digital file; and (c2) printing out saidwatermark-embedded digital file according to said option for controllingprinting.
 8. The method according to claim 7, wherein said option forcontrolling printing at said step (c1) comprises an option for settingthe number of print outs of said watermark-embedded digital file.
 9. Themethod according to claim 8, wherein said option for controllingprinting further comprises, in the state of setting said number of printouts, an option for commanding a memory to delete the latest documentsimultaneously with an end of printing command after the printingcommand has been executed.
 10. The method according to claim 7, whereinsaid option for controlling printing at said step (c1) comprises, anoption for displaying only an information of said securities, etc. to beissued or only an image of securities, etc. without watermark embeddedthereto on a screen of the user's terminal when said watermark-embeddeddigital file is printed out.
 11. An apparatus for issuing securities,etc. in printed-out form to a user, the apparatus comprising: an issuingmeans for issuing securities, etc. in the form of digital file; aterminal being connected with said issuing means through a network,transmitting an issuance-option by selection of said user of securities,etc. to said issuing means, and receiving securities, etc. according tosaid issuance-option from said issuing means; and print-out means beingconnected with said terminal, printing out said securities, etc.received from said terminal, wherein said issuing means comprises: meansfor generating a digital file of said securities, etc. and watermarkaccording to said issuance-option, and means for embedding saidgenerated watermark into said digital file of said securities, etc. 12.The apparatus according to claim 11, wherein said means for generatingwatermark generates said watermark by using at least one of a key-typemethod, a logo-type method, and a method simultaneously employing bothmethods.
 13. The apparatus according to claim 12, wherein saidgenerating watermark using a key-type method comprises, at least one ofgenerating said watermark by a plurality of keys in accordance withprimary information of said securities, etc. and generating saidwatermark using a checksum or hash-value obtained from the entireinformation of said securities, etc.
 14. The apparatus according toclaim 11, wherein said embedding watermark comprises, at least one ofembedding a robust watermark and a fragile watermark simultaneously, andembedding a semi-watermark into said digital file.
 15. The apparatusaccording to claim 14, wherein said fragile watermark and saidsemi-watermark are embedded with a controlled embedding level such thatsaid printed-out securities, etc. are detected only when said securitieshave experienced the first A/D conversion through a scanner, and saidprinted-out securities not being detected when said securities haveexperienced later A/D or D/A conversion.
 16. The apparatus according toclaim 11, wherein said issuing means further comprises an option forcontrolling printing of said watermark-embedded digital file.
 17. Theapparatus according to claim 16, wherein said option for controllingprinting comprises an option for setting the number of print out of saidwatermark-embedded digital file.
 18. The apparatus according to claim17, wherein said option for controlling printing further comprises, inthe state of setting said number of print outs, an option for commandinga memory to delete the latest document simultaneously with an end ofprinting command after the printing command has been executed.
 19. Theapparatus according to claim 16, wherein said option for controllingprinting at said step (c1) comprises, an option for displaying only aninformation of said securities, etc. to be issued or only an image ofsecurities, etc. without watermark embedded thereto on a screen of theuser's terminal when said watermark-embedded digital file is printedout.
 20. A method for authenticating watermark-embedded securities, etc.in the printed-out form, the method comprising the steps of: (d) readingsaid watermark-embedded securities, etc. in the printed-out form andconverting said securities, etc. to a digitalized image; (e) extractingwatermark embedded at an issuing apparatus from said digitalized image;(f) generating watermark from an information included in saiddigitalized image; and (g) determining authenticity of said securities,etc. by calculating a correlation between said extracted watermark andsaid generated watermark.
 21. The method according to claim 20, whereinsaid step (g) comprises the steps of: (g1) calculating a correlationbetween the extracted robust watermark and the generated robustwatermark; and (g2) calculating a correlation between extracted fragilewatermark and generated fragile watermark, and wherein the determinationof the authenticity of said securities, etc. is made based on whetherthe correlation calculation between said robust watermarks and betweensaid fragile watermarks satisfies a predetermined correlation condition.22. The method according to claim 20, wherein said step (g) comprises astep of: calculating a correlation between the extracted semi-watermarkand the generated semi-watermark, and wherein the determination of theauthenticity of said securities, etc. is made based on whether thecorrelation calculation between said robust watermarks and between saidfragile watermarks satisfies a predetermined correlation condition. 23.An apparatus for authenticating watermark-embedded securities, etc. inthe printed-out form, the apparatus comprising: an image A/D converterfor reading said watermark-embedded securities, etc. in the printed-outform and converting said securities, etc. to a digitalized image; and anauthenticating unit for extracting a watermark embedded at an issuingapparatus from said digitalized image, generating a watermark from aninformation included in said digitalized image, and determiningauthenticity of said securities, etc. by calculating a correlationbetween said extracted watermark and said generated watermark.
 24. Theapparatus according to claim 23, wherein said authenticating unitcomprises: means for calculating a correlation between the extractedrobust watermark and the generated robust watermark; and means forcalculating a correlation between the extracted fragile watermark andthe generated fragile watermark, and wherein the determination of theauthenticity of said securities, etc. is made based on whether thecorrelation calculation between said robust watermarks and between saidfragile watermarks satisfies a predetermined correlation condition. 25.The apparatus according to claim 23, wherein said authenticating unitcomprises: means for calculating a correlation between the extractedsemi-watermark and the generated semi-watermark, and wherein thedetermination of the authenticity of said securities, etc. is made basedon whether the correlation calculation between said robust watermarksand between said fragile watermarks satisfies a predeterminedcorrelation condition.